Piston recammer



D. J. WHERRY PISTON RECAMMER Oct; 7, 1941.

Filed July- 3, 1940 5 e WM, r K d m M FIG. 3

- portion 3 depending from the head. Inwardly Patented Oct. 7, 1941UNITED STATES PATENT OFFICE 2,258,476 rrs'ron nncamma Dale J. When-y,St. Louis, Mo. Application July 3, 1940, Serial N... 243,694

(or soc-12) 2 Claims.

This invention relates to improvements in piston construction and moreparticularly to means adapted to be used in connection with solid skirtpistons that have become worn or out-of-round, so as to re-cam thelatter or re-shape them to substantially their original shape.

the likelihood of causing the pistons to rapidly wear through along thepoints where the thrust holding them expanded is being exerted.

Other objects of this invention are to construct a device of the kinddescribed, which will be extremely simple in construction andinstallation, which shall not require any extraneous alterations orsecurement to the piston structure to retain the re-cammer securely inits place, of low cost, and which will be otherwise efiicient andsatisfactory for use wherever deemed appli- Cable.

Many other objects and advantages of the construction herein shown anddescribed, and the uses mentioned, will be obvious to those skilled inthe art to which this invention appeartains, as will be apparent fromthe disclosures herein given.

To this end, my invention consists in the novel construction,arrangement and combination of parts herein shown and described, and theuses mentioned, as will .be more clearly pointed out through a pistonshowing my device in operative position therein;

Figure 2 is a vertical cross-sectional view, with portions in elevation,taken substantially at right angles to Fig. 1;

Figure 3 is a transverse cross-sectional view,

taken substantially along the line 3 3 of Fig. 1;

Figure 4 is a diagrammatic plan view, showing the' piston before andafter re-shaping.

Referring mor particularly to the drawing,

wherein I have illustrated a preferredembodiment of 'my invention,thereis shown a piston of a well-known type, comprising a closed or headend I having the packing ring grooves 2 immediately therebelow, and withthe skirt or trunk vided on the interior of the skirt to define theupper and lower limits of the interior of the latter,"somewhat as shown.These pistons are preferably machine-ground to their peripheral contour,controlled .by some sort of a cam means. Inwardly directed projectionsor bosses 6-6 are formed about mid-height of the skirt, and into thesebosses there is secured the wrist pin I. It is to be particularly notedthat this .type of piston is not provided with any expansion slotthrough its skirt wall, extending substantially longitudinally upwardlyfrom its bottom edge, so that this type of piston is best described as asolid skirt piston, having no interruptions or openings about itscircumference, except of course thoseopenings shown to receive the endsof the wrist pin.

Although it is admittedly old to expand slotted skirt pistons, it ismuch more diiiicult to reshape worn solid-skirt pistons to theirsubstantially initially circular cross-section. One reason is becausethese pistons have unusually-thin skirts, running around .040" or .050"thick, and there is danger of wearing through with localized presureoutwardly through the skirt.

Solid skirt pistons of'the type shown are of steel or some othersimilarly strong material comparatively more resistant to expansion thanthe alloy or aluminium pistons of the slotted type. so that there-cammer or re-shaper must be strong enough to perform its intendedfunction and 'yet not damage the piston either in installation or inservice.

With this in mind, I have constructed a recammer or re-shaper adapted tobe'readily installed into the solid skirt steel piston, after the latterhas become worn or out-o -round, without the necessity of using anyfastening means or of doing any working upon the piston, this devicebeing simply snapped into position from the open end of the skirt andbeing thereafter retained in place by the inherent resiliency orspringiness metal, say about .02" thick, formed into a channel orU-shaped shell member 8 having the pair of spaced leg portions 9--!joined by the main body portion In. This intermediate portion 10 isprovided with an expansion fold or trough ll extending longitudinallycentrally thereof, this fold projecting outwardly beyond the main bodyportion 10, so that when the device is inserted in operative position,as shown in Fig. 3, only the terior of the skirt wall.

The edges of the legs are provided with arcuate or curved recesses I2intermediate their length, with the lower ends of the recessesprojecting outwardly a slight distance beyond the upper ends of thesame, as shown most clearly in Fig. 2, so that the device may beinserted into the position shown in Fig. 2 more readily.

The device is of such a size that when it is inserted into the skirt ofthe worn piston, the fold it is of substantially the same length as thepiston skirt, so that the fold portion is engaged at the top and bottomends by the shoulders 4 and 5.

The leg portions of the re-shaper are preferably tapered from the main.body portion to the free edges, not only to decrease the weight of thesame, but in order not to interfere with the normal movement of theconnecting rod, with the flow of lubricant within the piston, or in anyother manner decrease the efliciency of the cooperating parts.

The distance between the leg portions of the re-shaper are preferablyslightly greater than the distance between the abutments against whichsaid portions press after installation in the piston, so that it isrequired to slightly compress these legs during installation, whereuponthey spring apart after release of the installing tool.

The curved recesses of the leg portions snap onto and interlock with thewrist pin, partially embracing the latter, and. in addition they'abutthe opposed ends of the pin bosses, and it is obvious that the inherentresiliency of this onepiece re-shaper when sprung and snapped intoposition, will cause the latter to exert a laterally outward pressureagainst the unslotted skirt, suflicient to re-shape the skirt and causethe latter to resume its initially substantially circular shape,

this pressure being uniform and even for the full length of the skirt.

fold or rib portion II will engage with the in- In Fig. 4, the dottedlines indicate the out-ofround shape of the piston skirt (with the wristpin, not shown, in the direction indicated in Fig. 3), and the full lineindicates the shape after the re-shaper member has been snapped intoplace, the change in peripheral outline taking place entirely all alongthe skirt, and not being localized thereabout.

Having thus described my invention, it is obvious that variousimmaterial modifications may be made in the same without departing fromthe spirit of my invention; hence I do not wish to be understood aslimiting myself to the exact form,

arrangement, construction and combinations of parts shown, except aslimited by the state of the art to which this invention appertains andthe claims hereunto appended.

What I claim as new and desire to secure by Letters Patent is:

l. The combination with a piston having a substantiallycircumferentially-continuous skirt carrying an interior projection; of aspring metal readily detachable shell member sprung into place betweensaid projection and the interior of said skirt, said shell having anoutward expansion fold intermediate its lateral edges to engage andexert an outward thrust on said skirt therealong.

2. The combination with a piston having a substantiallycircumferentially-continuous skirt; and a wrist pin transversely throughsaid skirt; of a resilient channel-shaped cross-section member ofrelatively very thin metal having curved recesses in the edges and withan. outwardly projecting expansion fold intermediate said edges, so thatsaid member may be detachably sprung into place between said skirt andpin with substantially only said expansion fold engaging along theinteriorof the skirt and with said curved recesses partially embracingsaid pin.

DALE J. WHERRY.

